Pharmaceutical residues have been found in municipal wastewater and have raised concerns about the potential risks they pose to both humans and our ecosystems. Among the different AOPs, heterogeneous TiO2 photocatalysis is reported to be a promising technology for the degradation of such toxicants. The aim of this paper is to examine the degradation of various pharmaceutical compounds (Paracetamol, Naproxen and Ibuprofen) by the heterogeneous photocatalysis processes TiO2 / UV, UV-LED and solar irradiations. The operating parameters, namely, pH, catalyst load and light intensity (number of LEDs) were optimized. The main parameter of degradation as a function of pH was the adsorption of the molecules studied on the TiO2 entities. Thus, the rate of degradation increases as a function of the catalyst load, but the excess of catalyst load decreases the rate of degradation by opacity effect. The mineralization of the treated solutions was followed by the chemical oxidation demand (COD) measurement and/or the dissolved organic carbon (DOC). Significant mineralization was observed, however, no complete mineralization was observed in our study. Using different chromatographic techniques (HPLC) and ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS), an attempt was made to identify some reaction intermediates formed during the degradation of our molecules studied. Reaction mechanisms have been established according to the results obtained in order to try to understand the degradation of the compounds studied and their mineralization. The effect of the matrix on the degradation was examined and the effect of the present ions was studied. In photocatalysis TiO2 / solar, a study of the reusability of the supported TiO2 film was carried out and the film maintained a stable catalytic activity after five reuses. The toxicity of the molecules studied and of the reaction intermediates was monitored by the avoidance test on Eisenia andrei earthworms and by the Microtox test on Vibrio Fischeri bacteria. The results showed that photocatalysis reduced the toxicity of the molecules studied.

Photocatalytic pathway toward degradation of various pharmaceutical molecules: Kinetics, mechanisms and toxicity assessment

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.